An absorbent article refers to products such as diapers, sanitary napkins, training pants, incontinent garments, overnight pads, panty liners, under arm shields and the like, which are used to absorb body fluids, such as urine, menses, blood, perspiration and other excrements discharged by the body. Sanitary napkins, also referred to as catamenial pads, feminine pads, overnight pads, panty liners and panty shields are designed to be worn by a female to absorb menses and other body fluids discharged before, during and after a menstrual period. Sanitary napkins are external devices which are designed to be aligned approximate the pudendum region of a human body and are generally held in position by being adhesively or mechanically attached to an undergarment. Sanitary napkins also differ from panty liners and panty shields in several notable ways. Sanitary napkins are generally larger in size and have a more defined 3-dimensional configuration, are thicker in caliper and are bulkier in appearance than panty liners or panty shields.
Since sanitary napkins are normally used during major discharge portions of a menstrual period, they are constructed to absorb a greater quantity of body fluid and are designed so they can be worn for a longer period of time than a panty liner or a panty shield. Appropriately, sanitary napkins are constructed to handle medium to heavy flows and commonly have a total absorbent capacity in a range of about 20 to 50 grams of fluid.
Today's sociological changes have enabled women to become more active in sports and other types of physical activity. These changes have been complimented by a change in attire and have given women the option of wearing close body fitting clothing. Current sanitary napkins have a caliper of greater than 6 millimeters (mm) and can present a bulge adjacent to the pudendum when worn inside tight fitting shorts or pants. The overall size and configuration of the sanitary napkin can also restrict leg movement or cause discomfort when a woman participates in physical or sporting events. In view of this, there is a real need to develop a thin sanitary napkin which is less than about 5 mm in caliper is resilient and yet able to absorb as much body fluids as current available products.
In developing a thin sanitary napkin of less than about 5 mm in caliper, it has been realized that such products have a tendency to twist and bunch when worn. The squeezing of the sanitary napkin between the thighs and resulting deformation as a woman moves about causes the upper surface of the napkin to acquire curved or convex shape. This twisting and bunching is referred to as "roping" because the cylindrical profile can be imparted to the sanitary napkin. This roping effect is detrimental because the napkin is unable to absorb fluid that contacts its upper surface. The fluid discharged from the vagina has a tendency to run off the roped napkin before it can be absorbed. Therefore, the fluid leaks onto the undergarment. This run-off becomes significant during periods of heavy flow. It is therefore, desirable to construct an absorbent article which has the capacity to rapidly wick body fluids in the x-y plane to a large portion of the absorbent so as to prevent premature side leakage.
It is also desirable to construct an absorbent article having a resistance to roping and bunching of the napkin during use.